The present disclosure relates to an image processing apparatus, a ruled line determination method, and a storage medium having a ruled line determination program stored therein, configured to determine ruled lines in image data.
When a document, such as a notebook with ruled lines, on which characters and the like are handwritten by a pencil, a ball-point pen, or the like is coped, the document may be copied with a set density being enhanced in order to clarify faint characters in some cases. In this case, a print density for the ruled lines preprinted on the notebook as well as a print density for the copied handwritten characters is enhanced. Therefore, the ruled lines copied with the enhanced print density become a hindrance and the copied handwritten characters become unclear and are difficult to distinguish.
To date, a technique for eliminating ruled lines when a document is copied, in order to address such a problem, has been known. Specifically, a ruled line elimination method has been known in which, in image data in which characters and ruled lines are formed by the same color, a portion, of the image data, in which black pixels are continuous over a predetermined length or longer in the main scanning direction and the sub-scanning direction is estimated as a ruled line, and whether the estimated ruled line represents a ruled line or a character is determined according to an intersecting pattern between the estimated ruled line portion and a black image, thereby eliminating the ruled lines. Further, an image processing apparatus has been known which determines, after an image is changed into a monochrome image, that continuous pixels which are continuous over a predetermined threshold length or greater length represent one ruled line, and determines that continuous pixels which connect with the one ruled line with a specific intersecting pattern also represent another ruled line, to eliminate the one ruled line and the other ruled line.